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A synthesis method to obtain porous platinum-based macrotubes and macrobeams with a square cross section through chemical reduction of insoluble salt-needle templates is presented.
The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed by rinsing and supercritical drying steps, often resulting in mechanically fragile materials. Here, a method to synthesize nanostructured porous platinum-based macrotubes and macrobeams with a square cross section from insoluble salt needle templates is presented. The combination of oppositely charged platinum, palladium, and copper square planar ions results in the rapid formation of insoluble salt needles. Depending on the stoichiometric ratio of metal ions present in the salt-template and the choice of chemical reducing agent, either macrotubes or macrobeams form with a porous nanostructure comprised of either fused nanoparticles or nanofibrils. Elemental composition of the macrotubes and macrobeams, determined with x-ray diffractometry and x-ray photoelectron spectroscopy, is controlled by the stoichiometric ratio of metal ions present in the salt-template. Macrotubes and macrobeams may be pressed into free standing films, and the electrochemically active surface area is determined with electrochemical impedance spectroscopy and cyclic voltammetry. This synthesis method demonstrates a simple, relatively fast approach to achieve high-surface area platinum-based macrotubes and macrobeams with tunable nanostructure and elemental composition that may be pressed into free-standing films with no required binding materials.
Numerous synthesis methods have been developed to obtain high surface area, porous platinum-based materials primarily for catalysis applications including fuel cells1. One strategy to achieve such materials is to synthesize monodisperse nanoparticles in the form of spheres, cubes, wires, and tubes2,3,4,5. To integrate the discrete nanoparticles into a porous structure for a functional device, polymeric binders and carbon additives are often required6,7. This s....
CAUTION: Consult all relevant chemical safety data sheets (SDS) before use. Use appropriate safety practices when performing chemical reactions, to include the use of a fume hood and personal protective equipment. Rapid hydrogen gas evolution during electrochemical reduction can cause high pressure in reaction tubes causing caps to pop and solutions to spray out. Ensure that reaction tube caps remain open as specified in the protocol. Conduct all electrochemical reductions in a fume hood.
1. Mag.......
The addition of oppositely charged square planar noble metal ions results in near instantaneous formation of high aspect ratio salt crystals. The linear stacking of square planar ions is shown schematically in Figure 1, with the polarized optical microscopy images revealing salt needles that are 10’s to 100’s of micrometers long. A concentration of 100 mM was used for all platinum, palladium, and copper salt solutions. While the salt needle templates are charge neutral in that th.......
This synthesis method demonstrates a simple, relatively fast approach to achieve high-surface area platinum-based macrotubes and macrobeams with tunable nanostructure and elemental composition that may be pressed into free-standing films with no required binding materials. The use of Magnus’ salt derivatives as high aspect ratio needle shaped templates provides the means to control resulting metal composition through salt-template stoichiometry, and when combined with choice of reducing agent, control over the nano.......
This work was funded by a United States Military Academy Faculty Development Research Fund grant. The authors are grateful for the assistance of Dr. Christopher Haines at the U.S Army Combat Capabilities Development Command. The authors would also like to thank Dr. Joshua Maurer for the use of the FIB-SEM at the U.S. Army CCDC-Armaments Center at Watervliet, New York.
....Name | Company | Catalog Number | Comments |
50 mL Conical Tubes | Corning Costar Corp. | 430290 | |
Ag/AgCl Reference Electrode | BASi | MF-2052 | |
Cu(NH3)4SO4Ÿ•H2O | Sigma-Aldrich | 10380-29-7 | |
dimethylamine borane (DMAB) | Sigma-Aldrich | 74-94-2 | |
K2PtCl4 | Sigma-Aldrich | 10025-99-7 | |
Miccrostop Lacquer | Tober Chemical Division | NA | |
Na2PdCl4 | Sigma-Aldrich | 13820-40-1 | |
NaBH4 | Sigma-Aldrich | 16940-66-2 | |
Polarized Optical Microscope | AmScope | PZ300JC | |
Potentiostat | Biologic-USA | VMP-3 | Electrochemical analysis-EIS, CV |
Pt wire electrode | BASi | MF-4130 | |
Pt(NH3)4Cl2Ÿ•H2O | Sigma-Aldrich | 13933-31-8 | |
Scanning Electron Microscope | FEI | Helios 600 | EDS performed with this SEM |
Shelf Rocker | Thermo Scientific | Vari-Mix™ Platform Rocker | |
Snap Cap Microcentrifuge Tubes, 1.7 mL | Cole Parmer | UX-06333-60 | |
X-ray diffractometer | PanAlytical | Empyrean | X-ray diffractometry |
X-ray photoelectron spectrometer | ULVAC PHI - Physical Electronics | VersaProbe III |
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